Technical Field
The present disclosure relates to a monitoring device, an ion implantation device, and a monitoring method.
Related Art
An ion implantation device that implants impurities into a wafer, which is a semiconductor substrate, by generating an ion beam and radiating the generated ion beam onto the wafer, is known. The state of the ion beam has a large influence on the physical properties of the wafer, and there is therefore a demand to ascertain the state of the ion beam with high precision.
In the ion implantation device, a Faraday cup connected to an oscilloscope is provided, and a beam current produced by irradiation of the ion beam onto the Faraday cup is measured by the oscilloscope, enabling determination to be made as to whether or not the state of the ion beam is correct.
However, various types of noise are generated during the generation process and the irradiation process of the ion beam, and the generated noise is superimposed on the beam current. In a case in which the noise is superimposed on the beam current, this makes it difficult to determine with high precision whether or not the state of the ion beam is correct from the measurement results of the oscilloscope.
As technology that enables a highly precise determination as to whether or not the state of the ion beam is correct, a technology that subtracts noise components, measured similarly to the beam current, from current value integration data based on values of the beam current is known (for example, see Japanese Patent Application Laid-Open (JP-A) No. H07-57671).
However, although the above technology enables the approximate state of the beam current to be ascertained, noise is not entirely eliminated from the beam current, and is difficult to ascertain the noise that was not completely eliminated from the beam current.
Examples of noise not completely eliminated from the beam current include noise produced by causes such as degradation and fouling over time. Noise produced by causes such as degradation and fouling over time refers to, for example, noise produced as a result of insulating flaws being generated by degradation, fouling, and the like over time, at locations at which insulation must be maintained in order to apply the voltage required for ion beam formation. Likewise, noise produced by degradation or malfunction of a power source may not be eliminated from the beam current.